Electrical receptacles are common devices fastened to an end of an electrical conductor wire to allow connection with another electrical conductor wire that is fitted with an electrical plug. The receptacle contains a plurality of apertures, each of which access one conductor strand of the conductor wire. Each conductor wire is fastened to some type of coupling connector that is held within the receptacle at each aperture. FIG. 1 shows an example of one type of coupling connector that is fastened to a conductor wire. The plug contains a like number of blades, each of which is fastened to one conductor strand of the other conductor wire. Inserting the plug blades into the receptacle apertures, and the coupling connectors therein, connects the conductor strands of the two conductor wires, thereby making an electrical connection. In FIG. 1 the plug blade enters the vertical slot adjacent the two curved sections C of the coupling connector.
Many receptacles and plugs are produced separately and then fastened by hand to each conductor wire to provide suitable electrical connection for the conductor wires. A more permanent connector system employs molding of an electrically insulating plastic or rubber receptacle or plug directly on the end of a conductor wire. The coupling connectors or plug blades are first fastened to each strand of the conductor wire, then the outer covering is formed over the wire with blades or the coupling connector fastened thereto. Injection molding of the receptacle or plug end coverings of wires employs a molten thermoplastic material injected into a mold containing the appropriate wires with the appropriate connector end fastened thereto. The production of a receptacle generally employs some type of pin, positioned at each coupling connector, to form the aperture that later accepts the plug blade. After the thermoplastic material sets or cools, the mold and pins are removed, releasing the resulting receptacle or plug end of the wire.
The thermoplastic materials used to form the plug and the receptacle undergo shrinkage in the transformation from a hot molten condition to a cool solidified condition during the molding process. The magnitude of shrinkage for the thermoplastic materials is found to vary with the specific material used, as well as the process temperature and the environmental conditions present during production. Variation in material shrinkage causes variation in dimensions between the plug blades and, most importantly between the apertures accessing the coupling connectors within the receptacle. This problem is particularly important when producing small dimension receptacles and plugs. The plug blades extending from the molded plug provide some degree of adjustment by slight bending. The receptacle apertures and internal connectors cannot be adjusted to any degree. Thus, the molded receptacle requires production with high precision. Some examples of inventions concerned with electrical receptacles and plugs have been granted patents.
Suverison et al., in U.S. Pat. No. 4,043,630, disclose a molded plug connection including a preformed insert shown in detail in FIGS. 2-6. The insert has a front plate with four spaced apertures which each align with one of four spaced channels in the elongated turret .
U.S. Pat. No. 4,398,785 by Hedrick shows an inner body which is injection-molded about the contacts and the connectors which are attached to the contacts. Thereafter, an outer cover is injection-molded about the inner body.
In U.S. Pat. No. 4,405,194, van Lierop describes a pre-molded insert arrangement including a base holding a space connector pin. The base has a recess for receiving a fuse holder. The cap prevents liquid plastic from flowing into the fuse recess during injection molding of the plug body.
Feher et al., in U.S. Pat. No. 4,684,191, describe an electrical connector assembly having contact springs with an outward flare. A fork has tines defining a flared receptacle guiding mouth for receiving a bus bar.
Bowden, Jr. et al., in U.S. Pat. No. 4,775,332, disclose an electrical receptacle having terminals with a pair of grasping members to receive an electrical plug blade. The grasping members taper toward the open end and then flare outwardly.
In U.S. Pat. No. 4,897,052, Priest et al. describe an intermediate electrical component including a two-piece plastic insulating shell having a molded body portion for receiving a plurality of terminal elements and a molded cap portion for enclosing the terminal partially within the body portion and the cap portion. The cap portion is slidably inter-fitted with the body portion. Conductor wires are fastened to power blades, each with a blade section and a pair of resilient leaves, with the leaves adapted to receive another blade. The blades are fitted into the two piece insulating shell and the unit is covered with suitable insulating material by injection molding.
U.S. Pat. No. 5,137,474 by Lin discloses an AC electrical socket structure having conductive strips with U-shaped insertion folds held in place by mounting brackets. The folds are for receiving electrical plug blades.
Chiodo, in U.S. Pat. No. 5,171,168, describes an electrical "piggyback" plug made with a pair of unitary prong-socket members (FIGS. 1-4) having flat socket fingers and a gap there between for receiving a plug blade. The prongs and sockets of the plug are oriented at a 90-degree angle in the molded dielectric plastic body.
U.S. Pat. No. 5,378,161 by Loder shows an electrical connector with tapered male and female surfaces for use with a ribbon cable. The male connector has one conductor, and the female connector has several conductors.
Miller, in U.S. Pat. No. 5,486,121, discloses an electrical connector assembly with a socket subassembly and a distribution assembly. The socket assembly has socket busses with slits for receiving blades of electrical plugs.
In U.S. Pat. No. 5,560,981, Ito describes a double molded connector including a connector portion and an inside-outside communication portion which folds on itself to retain conductor strands in channels. The connector portion and inserted conductor strands of FIG. 7 are molded with insulating resin to produce a finished double molded connector of FIGS. 8 and 9.
Brown et al., in U.S. Pat. No. 5,616,041, discloses a female connector for a plastic molded receptacle. The female connector has a first arm and a second arm with a slot between them. A third arm and a fourth arm are perpendicular to the first and second arms and have a slot between them also. A crimping end secures the conductor wire to the female connector. The first slot includes chamfers at the rounded end, while the third and fourth arms have bent away ends. The slots each can accept a blade from an electrical plug. Two female connectors are employed in a molded receptacle shown in FIGS. 12-15.
In U.S. Pat. No. 5,655,925, Pon describes a female plug that includes an insulating base bracket, two symmetrical contact blades fastened to the base block, an insulating housing covering the block to hold the blades in place, and a two-line electrical wire inserted though a flange rear port on the housing and connected to the contact blades. The base block has a pair of rectangular holes that accept a pair of blades from a male plug, the plug blades contacting the contact blades of the female plug.
Thus, there is an unmet need for an electrical receptacle that can be produced by injection molding techniques with a high degree of dimensional stability in the resulting receiving apertures.